Manufacturing of Integral Stiffened Skin Panels

Project Information

MISSP

Grant agreement ID: 755641

DOI

10.3030/755641

Project closed

EC signature date 7 April 2017

Start date 1 May 2017

End date 30 June 2020

Funded under

• SOCIETAL CHALLENGES - Smart, Green And Integrated Transport

Total cost

€ 899 742,50

EU contribution

€ 899 742,50

Coordinated by

SOCIETE NATIONALE DE CONSTRUCTION AEROSPATIALE SONACA SA
Belgium

Periodic Reporting for period 3 - MISSP (Manufacturing of Integral Stiffened Skin Panels)

Reporting period: 2020-03-01 to 2020-06-30

Summary of the context and overall objectives of the project

The MISSP (Manufacturing of Integral Stiffened Skin Panels) project aimed at proposing new manufacturing routes for metallic aircraft cargo doors. The main objectives of MISSP project were the following:
• To achieve further development, integration and validation of metallic technologies such as innovative light-weight alloys, environmentally friendly and low-cost manufacturing processes, and innovative recycling concepts at the end of the product life cycle. This objective was met in WP1 for roll-forming and HEHF manufacturing processes, in WP2 for creep-forming and in WP3 for HEHF. Nevertheless, during WP1 investigations, stretch forming was proven not to be a good candidate and validation of the process was not possible.
• To characterize and evaluate the properties of new light high-strength alloys such as Al-Mg-Sc alloys. This objective was achieved through an extensive preliminary testing campaign which contained (D2.2): Laser beam welding of AA5024 and AA5028 samples, Hybrid laser-GMAW welding of AA5024 and AA5028 samples, Friction stir welding of AlMgSc sheet and Laser beam welding with cold filler wire, and an additional testing campaign at the end of the project which contained (D2.6): LBW of AA5028 base material with AA5025 filler wire in butt-joint and T-joint configuration and investigations of these welds: Intergranular corrosion, tensile tests, liquid penetrant testing, radiography investigations, hardness measurements…
• To develop and combine advanced manufacturing processes such as High energy hydroforming, Creep Forming, Laser or Friction Stir Welding. This objective was met through the manufacturing of WP2 (creep-forming and LBW) and WP3 demonstrators (HEHF).
• To optimize and automate these advanced manufacturing processes through experiments and numerical modelling to increase their efficiency, repeatability and security. All used processes (roll-forming, creep-forming and HEHF) were optimized before and during the manufacturing of the demonstrators. Besides, numerical modelling was performed for stretch-forming. Creep forming and HEHF were numerically modelled leading the manufacturing tests to a successful result.
• To design and manufacture metallic structures applying the developed technologies. This objective was met through WP2 and WP3 parts that were within tolerances. Unfortunately, roll formed WP1 parts were slightly outside the given tolerances of 1mm. HEHF WP1 parts were almost not formed and this process would need improvement in order to get conform parts.
• To validate the properties of the parts and structures after application of the forming and welding processes. One WP1 part was mechanically tested. As expected, material properties were not degraded by this manufacturing process. AA5028 specimens representative of the demonstrators were tested and an additional welding campaign with T-joint specimens with the same geometry than the demonstrators was performed. At the beginning of the project 3DMF carried out a testing campaign on a smaller part representative of the demonstrator.
• To assess the use of these manufacturing processes and advanced alloys for the production of future metallic airframe structures. D4.1 D4.2 and D4.3 presented the cost of the manufacturing of related parts. Besides, the estimation of serial production cost was made when possible.
• To reduce the overall lead time and production costs for the manufacturing of cargo door structures by limiting the number of parts and assembly operations. WP4 shall evaluate possible cost savings and lead time reduction associated to each of the three design concepts proposed in this project. In particular, the reduction of assembly operations was achieved in WP3 with the integral cargo door. Cost savings and improvements are given through the WP4 deliverables.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

For WP1, the main achievements were:
• Stretch-forming (D1.3) and roll-forming (D1.4) processes were investigated with the aim of removing chemical milling of the manufacturing process. Representative samples following the identified improvement tracks were used. Roll-forming using polyurethane counter forms was validated as manufacturing processes for WP1 demonstrators (objective 1 was achieve). Stretch-forming was not judged as a good candidate.
• Roll-forming was optimized, and the roll-forming parameters validated through iterative testing.
• Two WP1 demonstrators were manufactured, inspected and delivered. One of them was externally sanded and the other delivered as it was after roll-forming (D1.5).
• One additional WP1-half demonstrator was manufactured for tensile testing and tensile testing results reported in D1.6.
 
For WP2, the main achievements were:
• The reporting of the preliminary results performed during PR1 (D2.2).
• Three creep forming demonstrators manufactured beginning of September 2019 at NLR facilities were inspected at SONACA at the end of September 2019 (D2.6). D2.6 also include and additional welding investigations of Al-Mg-Sc alloys.

For WP3, the main achievements were:
• Numerical modelling: Simulations of high energy hydroforming (HEHF) for thin (WP1) and thick (WP3) material performed on last reporting period were reported (D3.1).
• Preliminary material investigations were reported. Apart from the activities performed in the first reporting period, the following tests were carried out: Fatigue, fracture toughness and residual stress measurements by two methods.
• Tooling development: Forming die for full scale test and machining jig were manufactured on this period (for HEHF WP1 and WP3 demonstrators).
• Three HEHF WP1 demonstrators were delivered to OASIS project on January 2020.
• WP3 demonstrator was high energy hydro-formed and machined during the end of 2019. It was delivered to Saab project on January 2020.

For WP4, the main achievements were:
• Detailed cost analysis of WP1 roll-forming manufacturing route
• Detailed cost analysis of WP2 creep-forming manufacturing route
• Detailed cost analysis of WP3 HEHF manufacturing route
• Cost comparison of the three manufacturing routes

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Manufacturing recurring costs (BOM and manufacturing) were estimated to approximately 4.250€ for WP1 and WP2 parts, and 19.670€ for WP3. Complete comparison including direct non-recurring costs is presented in Figure below. As it was a one-shot production, the purchase of the material was not customized and manufacturing routes were not optimized, some tasks were handmade instead of automatized, and some others were externalized. Costs of serial production (approximately 120 ship sets per month) were also estimated. The second Figure below contains the comparison between the three proposed manufacture routes. Price for WP3 demonstrator could be further reduced as not a complete estimation of serial production was provided in D4.3 (in particular, the use of a material not needing solution heat treating and quenching and the reduction in ageing, solution heat treating and quenching using batches).
WP1, WP2 and WP3 parts are not similar. WP1 only produces the external skin of the cargo door, WP2 solution consists on the external skin with three welded stringers, and WP3 demonstrator is an integral structure, an almost finished part. Therefore, the cost to produce these parts are not fully comparable. WP1 and WP2 demonstrators would need to be finished by OASIS project and the new expenses added to these calculations in order to give fully comparable values.

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missp-comparison1.jpg

missp-comparison2.jpg